I would say that your solution is just right. Is it the only one? Maybe not, but it is simple, inexpensive, effective and I can't think of any problems your solution would introduce as you have it set up right now.

Back in the phonograph days (who remembers back to when "stereo high-fidelity" was the latest advance in audio?), there were ground wires to run from the turntable to the preamp and/or amplifier as a hum-elimination solution.

Congrats!